Semiconductor devices (semiconductor chips) incorporated in miniaturized and highly sophisticated electronics devices, such as integrated circuits (ICs) and large scale integration (LSI) circuits, have recently become more highly integrated and have greater capacities. Semiconductor packages, which include such semiconductor chips, are accordingly required to be miniaturized (thinner), provided with more pins, and highly densified. One packaging technique developed to meet these requirements is a system in package (SiP), which stacks multiple semiconductor chips onto a single substrate. In particular, an SiP formed using three-dimensional (3D) packaging technology that stacks semiconductor chips in a three-dimensional manner is referred to as a chip-stack package. The chip-stack package achieves higher integration of semiconductor chips and shortens the length of wires. This increases the circuit operation speed and reduces the stray capacitance of wires. The chip-stack package is now widely used.
A known 3D packaging technique used to manufacture a chip-stack package is a wiring bonding technique. This technique stacks a plurality of semiconductor chips onto a substrate and electrically connects the electrodes of the semiconductor chips to the electrodes of the substrate with bonding wires. However, the wires are thin and a chip-stack package formed with this technique has high impedance. Thus, this technique may not be applicable for high-speed semiconductor chips. Moreover, this technique requires areas in the package where wire loops are formed and thereby enlarges the package.
Japanese Laid-Open Patent Publication No. 2006-179562 describes another 3D packaging technique used to manufacture a chip-stack package. With this technique, semiconductor chips, each of which includes through electrodes, are stacked onto a substrate, and the semiconductor chips are electrically connected to one another by the through electrodes. This technique shortens the length of wires as compared with the wire bonding technique and thus reduces the size of the package.